FIELD  MUSEUM  OF  NATURAL  HISTORY. 


PUBLICATION   178. 


GICAL  SERIES. 


VOL.  V,  No-  i 


NEW  METEORITES 


OLIVER  CUMMINGS  FAKRINGTON 
Curator,  Department  of  Geology. 


CHICAGO,  U.  S.  A. 

August  I,  1914. 


IRVINE, 


FIELD  MUSEUM  OF  NATURAL   HISTORY. 

PUBLICATION    178. 
GEOLOGICAL  SERIES.  VOL.  V,  No.  i 


NEW  METEORITES 


BY 


OLIVER  CUMMINGS  FARRINGTON 
Curator,  Department  of  Geology. 


CHICAGO,  U.  S.  A, 
August  i,  1914. 


-^xumu*r 

*\V<*K*itr  *  &* 

';-* 


NEW  METEORITES. 


BY  OLIVER  CUMMINGS   FARRINGTON. 


AHUMADA 

This  meteorite  was  found  in  the  spring  of  1909,  60  miles  east  of 
Ahumada,  State  of  Chihuahua,  Mexico.  The  latitude  and  longitude  of 
this  locality  are  30°  40'  N.,  105°  30'  W.  Nothing  is  known  of  the  time  of 
fall  of  the  mass.  Although  extended  search  was  made  in  the  region  for 
other  masses,  none  was  discovered.  Through  Mr.  Lazard  Cahn  the 
single  mass  found  was  procured  entire  by  the  Museum  (Mus.  No. 
MeySo).  Its  weight  was  n61bs.  (5  2, 548  grams).  The  general  shape  of  the 
mass  is  irregularly  ovoid,  its  longest  diameter  being  17  inches  (43  cm.) 
and  its  diameter  at  right  angles  to  this  10  inches  (25  cm.).  The  surface 
is  irregularly  roughened  and  pitted,  but  was  probably  somewhat  modi- 
fied by  weathering.  The  meteorite  is  an  iron-stone  composed  of  a 
spongy  mass  of  nickel -iron  the  pores  of  which  are  filled  with  chrysolite. 
In  weathering,  the  chrysolite  has  yielded  first  so  that  the  metal  projects 
in  points  and  ridges.  Some  portions  of  the  surface  appear  to  retain 
pittings  produced  during  the  aerial  flight  of  the  mass  but  these  may  be 
due  to  weathering.  The  general  appearance  of  the  mass  is  shown  in 
Plate  I,  Fig.  i,  and  the  appearance  of  a  section  in  Fig.  2  of  the  same 
plate.  The  meteorite  is  a  pallasite  of  Brezina's  Rokicky  group,  and 
is  the  first  iron-stone  meteorite  thus  far  reported  from  Mexico.  The 
chrysolite  of  the  meteorite  is  dark,  nearly  black  in  color,  and  as  it  appears 
in  sections  occupies  relatively  greater  space  than  the  nickel-iron.  Some 
of  the  chrysolite  masses  are  of  large  size,  one  noted  being  i  inch  (2.5  cm.) 
in  diameter.  Their  outlines  as  seen  in  section  are  nearly  always  angular 
rather  than  rounded  although  some  are  irregularly  rounded.  Still  the 
angular  character  of  the  chrysolite  is  not  so  strongly  marked  as  in  Eagle 
Station  for  example  and  the  meteorite,  so  far  as  this  character  is  con- 
cerned, may  be  regarded  as  more  or  less  intermediate  between  the  Kras- 
nojarsk  and  Rokicky  pallasites.  While  the  chrysolite  of  the  interior  is 
dark  and  opaque,  on  the  outer  border  of  the  meteorite,  where  it  has  been 
exposed  to  weathering,  it  is  reddish  brown.  In  small  grains  it  is  trans- 
parent and  colorless  to  smoky  green.  Penetrating  the  substance  of  the 
grains,  at  times  irregularly  and  again  in  more  or  less  parallel  layers,  a 
black,  opaque  substance  may  be  seen.  The  presence  of  this  undoubtedly 


2       FIELD  MUSEUM  or  NATURAL  HISTORY  —  GEOLOGY,  VOL.  V. 

gives  the  chrysolite  masses  their  opaque  appearance.  As  grains  of  the 
chrysolite  are  readily  attracted  by  the  magnet,  it  is  probable  that  this 
substance  is  magnetite.  On  etching  the  metallic  portions  of  the  meteorite 
the  three  alloys  of  the  trias  are  seen  to  be  present  with  kamacite  largely 
predominating.  The  alloys  are  irregularly  distributed  but  in  general 
kamacite  in  bands  1-3  mm.  wide  is  found  bordering  the  chrysolite.  Be- 
tween the  kamacite  bands  in  the  metallic  portion  a  narrow  dark-gray 
field  of  plessite  usually  occurs,  separated  from  the  kamacite  on  all  sides 
by  a  thin  ribbon  of  taenite.  The  outline  of  the  fields  of  plessite  does 
not  follow  the  direction  of  the  adjoining  edge  between  the  chrysolite 
and  kamacite.  It  is  usually  broadly  sinuous.  In  other  portions  of  the 
metallic  areas  a  different  arrangement  of  the  trias  occurs.  Broad,  ir- 
regularly shaped  kamacite  bands  separated  by  narrow  fields  of  plessite 
run  more  or  less  at  right  angles  to  the  direction  of  the  chrysolite  border. 
The  bands  have  swollen,  rounded  outlines  and  tend  to  subdivide  into 
twos  and  threes.  Well-marked  ribbons  of  taenite  surround  the  bands 
and  their  subdivisions.  Figures  of  this  character  may  be  noted  near  the 
lower  left-hand  corner  of  the  section  shown  in  Plate  I,  Fig.  2.  Of 
accessory  minerals  there  is  little  evidence.  A  silver- white,  rough, 
metallic  mineral  which  is  probably  schreibersite  occasionally  cuts  across 
the  nickel-iron  and  chrysolite  without  affecting  the  structure  of  either. 
It  also  occasionally  occurs  as  a  thin  layer  between  the  nickel-iron  and 
chrysolite.  The  specific  gravity  of  a  section  of  the  meteorite  weighing 
65  grams  was  found  to  be  4.76.  This  indicates  that  the  nickel-iron  and 
chrysolite  are  in  about  equal  proportions  by  weight. 


ARISPE 

In  1902  Ward*  described  an  individual  of  this  fall  having  a  weight  of 
something  over  40  kilograms,  the  exact  weight  not  being  stated.  This 
seems  to  have  been  the  only  individual  of  the  fall  known  at  that  time, 
but  the  writer  has  since  learned  through  Mr.  Edward  E.  Noon,  a  min- 
ing engineer  of  Sonora,  Mexico,  of  two  more  masses  which  evidently 
belonged  to  this  fall.  One  of  these  weighing  62  kilograms  (116  Ibs.)  is 
now  in  the  collection  of  the  United  States  National  Museum,  the  other 
weighing  9  kilograms  (20  Ibs.)  came  into  the  collection  of  this  Museum 
through  the  kindness  of  the  late  Prof.  W.  P.  Blake.  (Mus.  No.  Me  781). 
Mr.  Noon,  who  procured  both  these  additional  masses,  informs  the  writer 
that  they  were  found  in  1896  about  25  miles  northwest  of  Arispe.  Ward 
gives  the  locality  of  the  individual  which  he  described  as  about  1 5  miles 
northwest  of  Arispe  and  the  date  of  find  as  1898.  The  proximity  of  the 

*  Proc.  Rochester  Acad.  Sci.  4,  82-86. 


JULY,  1914.  NEW  METEORITES  —  FARRINGTON.  3 

two  localities  and  the  similarity  of  the  etching  figures  leave  no  doubt  that 
the  three  masses  all  belong  to  a  single  fall.  The  20  Ib.  mass  is  of  an 
ovoid  form  with  the  dimensions  4x6x8  inches.  Saucer-shaped  pits 
about  two  inches  broad  give  the  surfaces  a  generally  concave  character 
except  where  the  edges  of  the  pits  form  sharp  and  often  elongated 
ridges.  The  etching  figures  are  entirely  similar  to  those  described  by 
Ward  for  the  larger  mass. 


BISHOP  CANYON 

This  meteorite  (Mus.  No.  Me  1955)  was  obtained  from  Mr.  C.  D. 
Heaton,  who  stated  that  it  was  found  by  a  Mr.  Hammond  in  1912  near 
Bishop  Canyon,  San  Miguel  Co.,  Colorado.  The  exact  locality  of  the 
find  was  four  miles  west  of  Bishop  Canyon  and  seventeen  miles  west  of 
the  Dolores  River.  The  locality  is  near  the  Utah  line.  Although 
Bishop  Canyon  is  not  shown  on  ordinary  maps  it  is  an  established  name 
in  the  region  and  seems,  on  this  account,  to  be  a  better  name  for  the 
meteorite  than  the  indefinite  ones  Dolores  River  or  San  Miguel  Co. 
which  might  otherwise  be  suggested.  The  meteorite  is  of  iron  and  its 
weight  is  19  pounds  (8,607  grams).  It  is  a  complete,  single  individual 
and  is  all  that  is  known  of  the  fall.  The  form  may  be  described  as  a 
roughly  triangular  pyramid  terminating  at  the  summit  in  an  edge  rather 
than  a  point.  The  height  of  the  pyramid  is  about  six  inches  (15  cm.) 
and  the  length  of  each  side  of  the  base  is  about  six  inches  also.  All  the 
surfaces  show  considerable  pitting,  those  upon  the  sides  of  the  meteorite 
agreeing  in  a  general  way  with  one  another  and  differing  from  those  of 
the  base.  On  the  sides  of  the  pyramid  the  pits  vary  in  size  and  shape 
and  their  junctures  produce  irregular  projections  and  ridges;  on  the  base 
the  pits  tend  to  be  circular,  of  rather  uniform  size,  and  their  points  of 
union  project  in  cone-like  forms.  These  different  markings  appear  to 
the  writer  to  indicate  an  orientation  of  the  meteorite.  The  base  of  the 
pyramid  appears  to  have  been  the  rear  side  in  flight,  and  the  apex  of  the 
pyramid  the  front  side.  The  different  appearances  of  the  two  surfaces 
are  shown  in  Plate  II,  the  upper  figure  giving  a  side  view  of  the  pyramid, 
the  lower  its  base  or  rear  side  of  the  meteorite.  As  usual,  the  mass  was 
more  or  less  marred  and  cut  by  the  finders  in  an  effort  to  determine  its 
nature.  The  surface  shows  to  some  extent  a  reddish  oxidation,  but  this 
does  not  penetrate  to  any  great  depth  and  the  original  pittings  are  in 
general  so  well  preserved  that  a  rather  recent  fall  is  indicated.  Only  a 
single  small  fragment  having  a  surface  of  about  one  sq.  in.  (2.5  sq.  cm.) 
has  been  cut  from  the  meteorite.  This  shows  a  nickel- white  color  and 
on  etching  displays  fine  octahedral  figures.  These,  on  account  of  the 


4       FIELD  MUSEUM  OF  NATURAL  HISTORY  —  GEOLOGY,  VOL.  V. 

direction  of  the  section,  intersect  nearly  at  right  angles.  Owing  to  there 
being  little  difference  in  color  in  the  members  of  the  trias  the  figures 
are  not  striking,  but  their  elements  are  easily  distinguishable.  The 
kamacite  bands  are  short,  straight,  and  unequally  grouped.  The  kama- 
cite  is  granular.  The  taenite  ribbons  are  narrow  but  border  the  bands 
regularly  and  show  no  tendency  to  anastomose.  The  fields  are  scat- 
tered but  tend  to  be  of  relatively  large  size.  Often,  field-like  spaces 
are  filled  with  kamacite,  distinguished  from  similar  fields  of  plessite  by 
a  lighter  color.  The  plessite  of  the  fields  is  of  uniform  color  and  texture 
and  homogeneous.  A  single,  small  inclusion  of  a  rectangular  form,  of 
troilite  constitutes  the  only  accessory  mineral  observed.  A  qualitative 
test  of  a  dissolved  fragment  of  the  meteorite  reacted  for  nickel.  A 
quantitative  analysis  of  the  meteorite  has  not  been  made  as  yet. 


DAVIS  MOUNTAINS 

This  meteorite  was  found  in  the  northern  end  of  Davis  Mountains, 
Jeff  Davis  County,  Texas,  in  1903,  by  George  Duncan,  Jr.,  then  a  lad 
of  seven  years.  The  locality  of  the  find,  as  nearly  as  it  can  be  determined 
by  the  writer,  was  Lat.  30°  55'  N.,  Long.  104°  5'  W.  The  Davis  Moun- 
tains are  shown  on  the  Valentine  sheet  of  the  topographic  maps  of  the 
U.  S.  Geological  Survey.  The  unusual  nature  of  the  mass  was  recognized 
later  by  Mr.  George  H.  Duncan  of  Toyah,  Reeves  County,  Texas,  a 
town  about  50  miles  northeast  of  the  place  of  find,  and  in  1913  he  had 
it  brought  to  Toyah.  The  mass  was  then  exhibited  for  a  time  in  Fort 
Worth,  Texas,  where  a  small  fee  was  charged  for  the  privilege  of  examin- 
ing it.  Prof.  G.  M.  Butler  of  the  Colorado  School  of  Mines  was  among 
the  first  to  recognize  the  meteoric  nature  of  the  mass,  his  investigations 
having  been  made  on  a  piece  sent  to  him  for  testing.  He  obtained  the 
usual  figures  of  a  medium  octahedrite  by  etching,  and  determined  by 
analysis  the  composition  —  Fe  92.20%,  Ni  7.54%.  Specific  gravity 
7.37.  This  information  Prof.  Butler  kindly  furnished  the  Museum 
through  correspondence.  In  September,  1913,  the  entire  mass,  with  the 
exception  of  about  5  Ibs.  that  had  been  removed  for  testing,  was  secured 
by  the  Museum  (Mus.  No.  Me  1946).  It  is  an  iron  meteorite  weighing 
1,520  pounds  (688  kgs.)  and  is  thus  of  unusually  large  size.  Like  many 
other  meteorites,  the  shape  of  this  meteorite  is  a  low,  irregular  cone, 
although  the  cone  is  so  low  that  the  form  might  perhaps  better  be 
described  as  shield-shaped,  with  the  boss  of  the  shield  corresponding  to 
the  apex  of  the  cone.  Further,  the  shield  has  a  roughly  triangular 
rather  than  oval  outline.  On  two  sides  of  the  triangle  (one  long  and 
one  short)  the  edge  of  the  shield  is  about  a  foot  (30  cm.)  thick  and  is 


JULY,  1914.  NEW  METEORITES  —  FARRINGTON.  5 

nearly  vertical  or  inclined  inwards  from  front  to  back.  On  the  remain- 
ing side  the  edge  narrows  down  to  close  contact  between  the  front  and 
rear  sides.  The  greatest  and  least  diameters  of  the  front  surface  of 
the  shield  are  32  inches  (78  cm.)  and  26  inches  (68  cm.).  The  mass  is 
well  oriented,  there  being  notable  differences  in  the  markings  and  appear- 
ance of  the  front  or  apical  side  as  compared  with  those  of  the  rear  or 
basal  side.  The  boss  of  the  shield  is  not  centrally  located  as  regards  the 
outline  of  the  shield,  but  is  much  at  one  side.  However,  it  appeared 
from  the  behavior  of  the  mass  in  handling  it  for  installation  that  this 
boss  or  apex  is  close  to  the  center  of  gravity  of  the  mass.  The  boss  does 
not  present  a  broad,  smooth  surface,  as  is  frequent  with  meteorites  of 
this  form,  but  is  roughened  and  furrowed.  The  furrows  extend  radially 
from  the  boss  over  a  considerable  part  of  the  front  surface  of  the  mass. 
They  doubtless  mark  the  course  of  air  currents  which  diverged  from  the 
boss  as  the  meteorite  passed  through  the  earth's  atmosphere.  The 
tendency  of  a  meteorite  in  passing  through  the  atmosphere  to  acquire 
a  conical  form  through  the  greater  erosion  by  atmospheric  currents  of 
the  periphery  of  its  front  is  illustrated  in  the  accompanying  diagram, 
Fig.  i .  The  front  portion  of  the  meteorite  may  be  considered  as  subjected 
to  both  vertical  and  lateral  forces  of  erosion.  The  resultant  force 
will  therefore  be  represented  by  a  diagonal  which  is  greater  than 
either  and  moves  in  a  direction  tending  to  produce  a  conical  form.  Other 
portions  of  the  meteorite  are  acted  upon  by  only  one  of  these  forces  and 
hence  are  less  affected.  If  the  meteorite  is  relatively  broad  in  proportion 
to  its  thickness,  the  lateral  force  becomes  stronger  and  the  broad 
surface  tends  to  be  maintained. 

Passing  from  a  consideration  of  the  general  form  of  the  Davis  Moun- 
tains meteorite  to  its  superficial  markings,  its  front  surface  will  be  found 
to  be  irregularly  indented  by  depressions  covering  several  square  inches 
each.  These  are  secondarily  modified  by  smaller  depressions  which 
resemble  the  more  usual  meteorite  pittings  except  that  they  are  irregular 
and  ill-defined.  Interspersed  with  these  depressions  are  long  ridges, 
the  longest  of  which  extends  in  an  irregular  course  from  the  boss  to  the 
most  distant  point  of  the  meteorite.  The  surface  of  this  ridge  is  marked 
by  a  brighter  luster  and  lighter  color  than  the  rest  of  the  mass.  At  the 
end  of  the  meteorite  farthest  from  the  boss  this  ridge  passes  over  the 
thick,  perpendicular  edge  of  the  meteorite  in  a  sinuous  course.  This  is 
at  the  apex  of  the  triangle.  The  ridge  is  also  strikingly  marked  by  a 
continuous  series  of  striae  running  in  a  direction  nearly  normal  to  its 
course.  These  striae  vary  in  length  and  depth,  but  none  of  them  is  over 
a  foot  in  length  or  more  than  a  millimeter  deep.  While  in  a  general  way 
they  all  take  the  same  course,  there  are  some  deviations  and  some  of  the 


FIELD  MUSEUM  OF  NATURAL  HISTORY  —  GEOLOGY,  VOL.  V. 


longer  ones  are  curved.  Except  at  one  point  the  striae  are  confined  to 
one  side  of  the  ridge,  the  perpendicular  side  shown  in  Plate  III.  On 
the  other  side  of  the  ridge  a  small  area  shows  striae  running  parallel  with 
the  ridge  and  directed  toward  the  boss.  The  ridge  evidently  served  to 
deflect  the  air  current  on  the  perpendicular  side  at  right  angles,  but  on 
the  other  side,  which  was  flatter,  their  normal,  radial  course  was  little 


Fig.  i.     Diagram  showing  how  erosion  by  air  currents  tends  to  produce  a  conical 
form  in  a  falling  meteorite. 

changed.  The  striated  side  of  the  ridge  is  also  smoothed  and  presents 
generally  convex  rather  than  concave  surfaces.  Further,  the  slopes  of 
the  secondary  depressions  on  this  side  are  abrupt  rather  than  gradual. 
Besides  this  main  ridge,  several  smaller  ridges  produced  by  the  meeting 
of  broad  depressions  appear  on  the  front  surface  of  the  meteorite,  and 
besides  the  broad  depressions  and  striations  of  the  front  surface  there 
may  be  noted  deep,  narrow  pits  and  crevices  which  penetrate  into  the 
mass  of  the  meteorite.  The  longest  of  these  is  shown  near  the  upper 


JULY,  1914.  NEW  METEORITES  —  FARRINGTON.  7 

right-hand  corner  of  Fig.  i,  Plate  IV.  This  pit  has  a  depth  of  about 
two  inches,  a  length  of  about  three  inches,  and  a  width  of  about  one  inch. 
Its  depth  is  in  the  direction  of  movement  of  the  mass.  The  edges  and 
whole  interior  of  the  pit  are  rounded.  At  one  end  it  runs  off  into  a  nar- 
row and  irregular  crevice.  Another  pit  of  this  same  general  nature  may 
be  seen  below  the  boss  in  Fig.  i ,  Plate  IV.  It  is  smaller  and  shallower. 
Several  cylindrical  pits  half  an  inch  or  less  in  diameter  are  also  scattered 
over  the  front  surface  of  the  meteorite,  their  depth  being  in  the  direction 
of  movement  of  the  mass.  A  long,  irregular  crevice  shown  at  the  left 
in  the  side  view,  Plate  III,  may  also  be  noted  among  the  markings  of 
the  front  surface.  All  these  deep  pits  and  crevices  are  probably  produced 
by  the  melting  out  of  some  fusible  constituent  or  the  enlargement  of 
some  lines  of  cleavage.  While  the  surface  of  the  meteorite  just  described 
was  undoubtedly  the  front  one  in  descending,  it  was  not  the  one  upon 
which  the  meteorite  lay.  On  the  contrary  it  was  that  which- was  upper- 
most. This  is  shown  by  its  greater  brightness  and  smoothness  as  com- 
pared with  the  opposite  side.  A  plainly  marked  soil  line  passes  around 
the  meteorite  approximately  along  the  median  line  of  the  edge  of  the 
shield  and  the  discoloration  and  oxidation  of  the  surface  below  this  line 
show  the  mass  to  have  been  imbedded  in  soil  to  this  depth.  Like  many 
other  iron  meteorites,  this  one  seems  to  have  turned  on  striking  so  that 
the  front  side  lay  uppermost. 

The  sides  of  the  shield  are,  as  has'  been  said,  in  part  perpendicular 
and  in  part  sloping.  Where  they  are  perpendicular  the  meteorite  is 
thick,  where  sloping,  thin.  The  striae  of  the  ridge  previously  described 
pass  partly  over  the  thick,  perpendicular  side  of  the  meteorite  and  as 
a  rule  terminate  rather  abruptly  about  half-way  over  the  side.  Along 
the  line  of  termination  may  be  seen  partly  turned-over  edges  like 
those  which  characterize  other  iron  meteorites  such  as  Algoma  and 
N'Goureyma. 

The  rear  side  of  the  meteorite,  shown  in  Fig.  2,  Plate  IV,  is  more  uni- 
formly and  deeply  pitted  than  the  front  side.  The  pits  are  broad,  irregu- 
lar, shallow  depressions  of  a  relatively  uniform  depth  of  one  half  to  one 
inch  (1-2  cm.).  There  are  no  striations  on  the  rear  side  as  there  are  on 
the  front  side.  The  pittings  of  the  rear  side  are  quite  uniform  in  their 
general  appearance  except  over  a  triangular  area  covering  about  a  foot 
square  and  sharply  depressed  below  the  general  surface.  Here  the 
pittings  are  much  smaller  and  in  addition  numerous,  slightly  rounded, 
semi-angular  protuberances  project.  These  protuberances  are  evi- 
dently cleavage  angles  rounded  by  fusion.  The  area  is  shown  at  the 
right  in  the  figure  previously  referred  to  (Fig.  2,  Plate  IV).  This  area 
was  evidently  produced  by  the  separation  of  a  portion  of  the  meteorite 


8       FIELD  MUSEUM  OF  NATURAL  HISTORY  —  GEOLOGY,  VOL.  V. 

during  the  fall  of  the  mass  to  the  earth  and  the  freshly  exposed  surface 
was  less  smoothed  and  pitted  than  that  which  was  exposed  dur- 
ing the  entire  course  of  the  fall.  As  is  usual  with  iron  meteorites  that 
have  passed  through  several  hands,  this  one  has  been  cut  and  chiseled  in 
various  places  in  order  to  remove  small  pieces  for  examination  or  to  test 
its  hardness.  The  injury  to  the  mass  in  this  way  has  fortunately  not 
been  great,  however.  The  largest  amount  so  cut  off  has  been  from  the 
portion  which  stands  uppermost  in  Fig.  i ,  Plate  IV.  From  this  portion 
about  5  Ibs.  have  probably  been  removed.  The  iron  saws,  breaks,  or 
files  rather  readily,  being  comparatively  soft.  It  is  highly  lustrous,  and 
of  a  zinc- white  color.  Portions  broken  off  show  marked  octahedral  cleav- 
age. The  iron  etches  quickly  with  dilute  nitric  acid  and  shows  octahedral 
figures  of  medium  width.  It  belongs  therefore  to  the  class  of  medium 
octahedrites.  The  figures  do  not  stand  out  prominently  even  on  pro- 
longed etching,  but  are  sufficiently  well  marked  for  identification.  The 
bands  are  relatively  long,  some  being  one  inch  (2.5  cm.)  in  length.  They 
are  also  straight  and  considerably  grouped.  The  kamacite  appears  to 
be  granular  rather  than  hatched  and  is  remarkably  homogeneous.  The 
taenite  borders  are  very  narrow  and  rarely  continue  throughout  the 
length  of  a  band.  As  a  rule  they  thin  out  and  disappear  though  main- 
taining their  direction.  Fields  are  almost  entirely  lacking  and  where 
they  do  occur  appear  to  be  minute  spaces  bordered  by  taenite  and  con- 
taining plessite  much  darker  in  color  than  the  kamacite.  No  accessory 
minerals,  such  as  troilite  or  schreibersite  have  been  observed  by  the 
writer  in  any  of  the  sections  thus  far  examined. 

A  chemical  analysis  of  the  meteorite  was  made  by  Mr.  H.  W.  Nichols, 
the  material  for  analysis  being  obtained  from  several  borings  with  a  */i 
inch  drill  to  a  depth  of  one  or  two  inches.  As  Mr.  Duncan  had  stated 
that  an  assayer  reported  platinum  in  the  mass,  careful  search  was  made 
for  this  metal  in  a  separate  portion.  The  method  employed  for  deter- 
mining platinum  was  a  modification  of  that  for  determining  copper  in 
iron  and  steel.*  The  material  used  was  in  the  form  of  very  coarse  borings 
which  enclosed  some  thin  seams. of  oxide.  The  weight  taken  was  5.1648 
grams.  This  was  placed  in  a  Jena  beaker  and  treated  with  i  :i  HC1  cold. 
The  beaker  was  placed  on  the  edge  of  a  hot  plate  and  after  action  was 
well  started,  water  was  added  from  time  to  time  in  such  quantities  that 
solution  attacked  the  borings  with  exceeding  slowness.  The  solution 
was  kept  hot  but  not  boiling  and  action  was  allowed  to  continue  for 
two  days,  when  the  borings  were  nearly  all  consumed.  The  residue, 
which  was  coarse  and  black,  was  small  in  quantity  and  contained  some 
un dissolved  iron.  When  this  stage  was  reached  the  beaker  was  removed 

*  Lord's  Metallurgical  Analysis,  3rd  ed.,  p.  163. 


JULY,  1914.  NEW  METEORITES  —  FARRINGTON.  9 

from  the  hot  plate  and  cooled  to  room  temperature.  H2S  was  then  passed 
in  to  saturation  and  the  solution  heated  very  slowly  to  boiling  and 
boiled  for  fifteen  minutes,  the  current  of  H2S  being  continued.  A  small 
black  precipitate  was  formed  which  was  filtered  off  and  ignited  in  a 
porcelain  crucible.  The  ignited  precipitate  was  dissolved  in  aqua  regia, 
evaporated  three  times  with  HC1,  diluted  and  filtered.  The  residue, 
which  was  very  small,  was  of  brownish  color,  translucent  and  gritty. 
It  gave  no  indication  of  the  presence  of  any  undissolved  iridium.  The 
filtrate  was  evaporated  nearly  to  dryness,  made  alkaline  with  ammonia 
and  a  few  flecks  of  iron  filtered  off  and  reprecipitated  three  times.  The 
filtrate  was  of  a  very  pale  blue  color.  This  filtrate,  evaporated  to  a 
volume  of  a  few  drops  in  a  porcelain  crucible,  was  made  acid  by  HC1  and 
ammonium  chloride  and  alcohol  added  to  precipitate  any  platinum.  A 
crystalline,  pale  yellow  precipitate  of  ammonium  platinic  chloride  was 
thus  obtained.  It  was  filtered  on  paper,  ignited  over  a  Meeker  burner 
and  weighed.  The  weight  obtained  was  also  checked  by  separating  the 
platinum  from  the  crucible  and  weighing  it  alone.  The  ignited  precipi- 
tate had  the  appearance  of  a  steel-gray  film,  with  a  granular  surface 
which  looked  like  a  film  of  very  fine  sand  with  coherent  grains.  It  was 
fairly  firm  and  stood  handling  with  ivory-pointed  forceps  without  break- 
ing. When  boiled  with  strong  HC1,  it  was  unaltered.  It  dissolved  in 
aqua  regia  without  residue  to  a  brown  solution  which  was  nearly  opaque 
when  very  concentrated.  After  removal  of  chlorine  and  nitrous  oxides 
by  six  evaporations  to  dryness  with  HC1,  the  solution  gave  a  strong 
rose  color  with  potassium  iodide.  The  ammonium  platinum  chloride 
was  reprecipitated,  and  appeared  under  the  microscope  as  yellow 
octahedrons.  No  platinum  vessels  or  instruments  were  used  in  any  of 
these  operations. 

The  total  results  of  the  various  operations  of  analysis  were  as  follows: 

Fe 92 . 03 

Ni 7.40 

Co 0.32 

Cu o.ooi 

Pt o .  03 

S o.ii 

P o.ii 

Si .  .  .     o .  08 


100.08 

The  analysis  shows  that  the  meteorite  has  the  composition  charac- 
teristic of  the  medium  octahedrites,  with  the  addition  of  a  small  per- 
centage of  platinum,  the  largest  that  has  yet  been  shown  to  be  possessed 
by  any  meteorite.  It  is  possible,  however,  that  platinum  is  a  more  con- 
stant ingredient  of  meteorites  than  records  show,  since  it  is  only  within 
the  last  few  years  that  it  has  been  looked  for  to  any  great  extent. 


io     FIELD  MUSEUM  OF  NATURAL  HISTORY  —  GEOLOGY,  VOL.  V. 

KILBOURN 

This  meteorite  fell  June  16,  1911,  at  about  5.  20  p.  M.,  on  the  farm 
of  William  Gaffney,  ^  miles  northeast  of  Kilbourn,  Wisconsin.  The 
latitude  and  longitude  of  this  locality  are  43°  40'  N.,  89°  40'  W.  The  only 
observer  of  the  fall  of  the  meteorite  was  Mr.  Gaffney,  and  to  him  through 
H.  Conrad  Meyer  of  the  Foote  Mineral  Company  the  writer  is  chiefly 
indebted  for  an  account  of  the  fall. 

Mr.  Gaffney  states  that  at  the  time  of  the  fall  he  was  in  his  hay 
field  about  20  rods  from  his  barn.  While  there  he  heard  a  rumbling  noise 
similar  to  that  produced  by  a  heavy  wagon  passing  over  a  stony  road. 
The  noise,  he  states,  was  much  louder  than  thunder.  The  day  was  close 
and  muggy  with  no  breeze  and  no  sign  of  a  local  thunder  storm.  The 
noise  lasted  about  three  or  four  minutes.  While  it  was  going  on  Mr.  Gaff- 
ney walked  towards  the  barn  and  when  he  entered  it  the  sound  ceased. 
When  he  had  been  in  the  barn  about  a  minute  he  heard  a  loud  report 
like  that  of  a  cannon  and  saw  a  small  stone  strike  the  manger  about 
iq  feet  from  where  he  was  standing,  rebound,  strike  the  stone  founda- 
tion of  the  barn,  and  then  bury  itself  to  a  depth  of  2^  inches  in  the 
hard-packed  clay  soil  which  formed  the  floor  of  the  barn.  Mr.  Gaffney 
picked  up  the  stone,  but  found  it  so  warm  he  could  hold  it  only  for  a 
second  or  so.  It  remained  warm  nearly  three  hours.  When  first  picked 
up  it  had  a  straw  color  on  its  surface,  but  gradually  assumed  a  black 
color.  Neighbors  of  Mr.  Gaffney  within  a  radius  of  three  miles  heard 
both  a  rumbling  noise  and  a  report  when  the  stone  struck  the  barn. 
Fishermen  at  Lake  Mason,  near  Briggsville,  Marquette  County,  Wis- 
consin, about  five  miles  east  of  Mr.  Gaffney's  place,  also  heard  a  rum- 
bling noise.  On  examining  the  barn  after  the  fall  of  the  stone  Mr.  Gaffney 
found  that  the  stone  had  gone  through  the  roof,  penetrated  three  thick- 
nesses of  shingles  and  a  hemlock  board  about  i  inch  thick;  then,  about 
4  feet  below  this,  passed  through  a  i/i  inch  hemlock  board  forming  the 
floor  of  a  hay-loft.  The  portion  of  the  floor  of  the  hay-loft  penetrated 
by  the  meteorite  was  submitted  to  the  writer  for  examination,  and  a 
photograph  of  the  same  is  shown  in  Plate  VI.  The  hole  said  to  have 
been  made  by  the  meteorite  is  about  4  inches  long  by  2  inches  wide,  and 
is  about  the  size  and  shape  that  such  a  projectile  would  have  made.  The 
shape  of  the  hole  indicates  that  the  meteorite  was  moving  in  the  direction 
of  its  longest  axis  and  not  broadside  when  it  penetrated  the  board.  It 
does  not  seem  to  be  possible  to  determine  positively  from  the  shape 
of  the  opening  which  end  of  the  meteorite  was  in  front,  although  the 
indications  are  that  it  was  the  pointed  end.  The  meteorite  fits  the  open- 
ing in  the  board  a  little  better  in  this  position,  yet  the  opposite  end  of  the 


JULY,  1914.  NEW  METEORITES  —  FARRINGTON.  n 

meteorite  shows  abrasion  and  removal  of  the  crust  in  several  places,  in 
a  manner  that  might  have  been  caused  by  the  striking  of  this  end  against 
boards.  The  penetrated  board  has  the  brittleness  peculiar  to  hemlock 
and  hence  might  offer  less  resistance  to  a  falling  body  than  some  other 
kinds  of  wood.  The  barn  stands  in  a  north  and  south  direction  with 
the  roof  sloping  east  and  west.  The  stone  fell  upon  the  east  slope  of  the 
roof  and  appears  to  have  come  from  a  direction  a  little  south  of  east. 

The  stone  is  comparable  in  size  and  shape  to  a  man's  fist.  Its 
appearance  on  several  different  sides  is  shown  in  Plates  V  and  VI.  It 
weighed  a  little  less  than  2  pounds,  the  exact  weight  being  27^  ounces, 
or  772  grams.  The  specific  gravity  of  the  stone  as  a  whole  was  3.43. 
Its  length  was  4^2  inches  (11.5  cm.),  width  3  inches  (8  cm.)  and  height 
2]/2  inches  (6  cm.).  One  relatively  broad,  though  somewhat  rounded, 
surface  forms  a  base  from  which  the  other  surfaces  rise  more  or  less 
irregularly.  These  irregular  surfaces  nearly  all  show  pitting  such  as 
usually  characterizes  meteorites,  but  the  pits  are  especially  numerous 
over  the  concave  surfaces.  The  pits  are  shallow,  irregular  in  outline, 
and  have  an  average  diameter  of  about  ^  inch  (6  mm.).  More  unusual 
than  the  pitted  surfaces  are  two  nearly  plane  surfaces  each  of  about  one 
square  inch  (2.5  sq.  cm.)  in  area  which  come  together  with  a  third  slight- 
ly pitted  surface  to  form  a  rather  steep  pyramid  at  one  end  of  the  stone. 
This  aspect  of  the  stone  is  shown  in  Plate  VI.  This  end  of  the  stone 
resembles  a  tool  shaped  for  piercing  or  boring.  On  the  edges  produced 
by  the  joining  of  these  three  planes  there  is  a  marked  smoothing  of  the 
crust,  its  surface  being  compact  and  glossy.  This  smoothing  extended 
on  one  edge  for  about  4  inches  (10  cm.),  on  the  other  two  about  one 
inch  (2.5  cm.).  It  may  have  been  due  to  the  friction  of  passing  through 
the  boards  of  the  roof  and  loft  if  this  portion  of  the  meteorite  was  in 
front,  but  whether  such  was  really  the  case  the  writer  is  unable  to  state. 

The  meteorite  when  received  was  nearly  covered  by  a  black  crust. 
Where  the  crust  was  lacking  the  lack  was  evidently  due  to  abrasion  from 
striking  the  barn  and  to  the  removal  of  portions  by  the  finder  for  exami- 
nation. The  crust  was  dull,  rough,  thin,  and  adhered  firmly  to  the  in- 
terior. Under  the  lens  its  surface  is  seen  to  be  covered  by  a  network  of 
little  ridges  of  matter  which  had  been  formed  by  flowing  when  in  a  fused 
state.  No  definite  drift  of  these  ridges  could  be  discerned.  While  much 
of  the  meteorite  is  covered  with  crust  of  this  character  over  some  sur- 
faces the  crust  takes  the  form  of  little,  dark,  glassy  spherules  thickly 
scattered  over  the  gray  surface  of  the  interior.  The  continuous  crust 
is  more  or  less  penetrated  by  meandering  cracks  which  give  the  surface 
a  crackled  appearance.  While  the  general  color  of  the  crust  is  black, 
at  the  bottom  of  many  of  the  pits  and  in  the  shelter  of  overhanging  edges 


12     FIELD  MUSEUM  OF  NATURAL  HISTORY  —  GEOLOGY,  VOL.  V. 

it  has  a  reddish  color,  indicating  a  higher  oxidation  of  iron  at  these 
points.  The  color  of  the  interior  of  the  stone  is  gray,  more  or  less  tinged 
with  brown  from  iron  oxide.  The  texture  is  compact  and  so  firmly  co- 
herent that  it  can  be  broken  only  with  difficulty.  Surfaces  take  a  good 
polish.  There  is  an  abundant  admixture  of  metallic  grains  in  the  stone. 
These  are  of  small  size  and  uniformly  distributed.  As  seen  on  a  polished 
surface  they  are  very  irregular  in  outline  but  at  times  elongated.  They 
rarely  exceed  }4  mm.  in  diameter.  Nearly  all  consist  of  nickel-iron  but 
a  few  show  by  their  yellow  color  that  they  are  troilite.  The  siliceous 
ingredients  of  the  stone  are  largely  in  the  form  of  chondri,  plainly 
distinguishable  on  a  polished  surface  by  their  circular  outlines.  Some 
of  the  chondri  are  black  in  color,  others  are  dark  gray  and  others  light 
gray.  The  largest  chondrus  noted  has  a  diameter  of  2  mm. ;  the  average 
are  about  half  that  size.  The  chondri  as  a  rule  break  with  the  stone  but 
occasionally  separate  out,  especially  on  polished  surfaces.  The  mega- 
scopic characters  seem  to  place  the  stone  in  Brezina's  class  of  sphemlitic 
chondrites. 

Under  the  microscope,  chondri  are  seen  to  largely  characterize  the 
structure  of  the  meteorite  though  their  quantity  is  not  as  great  as  in 
some  meteorites.  The  ground  mass  is  for  the  most  part  well  crystallized, 
the  crystals  being  large  and  with  definite  outlines.  The  prevailing  min- 
erals both  of  the  chondri  and  ground  mass  are  chrysolite  and  enstatite, 
chrysolite  being  the  more  abundant  of  the  two.  The  chondri  present  the 
usual  porphyritic,  radiated  and  lamellar  forms.  Of  especial  note  among 
the  lamellar  forms  is  one  in  which  the  lamellae  run  in  three  directions  at 
angles  of  60°.  The  three  series  of  lamellae  have  different  extinction 
angles  and  the  border  zone  extinguishes  in  unison  with  one  set  of  the 
lamellae. 

The  crust  is  thin  for  a  meteorite  so  coarse  in  structure  and  nowhere 
in  the  sections  examined  by  the  writer  shows  an  absorption  zone.  The 
outer  or  fusion  zone  is  very  nearly  one-tenth  of  the  thickness  of  the 
impregnation  zone.  The  thickness  of  the  two  zones  combined  approxi- 
mates closely  to  0.4  mm.  The  impregnation  of  fused  matter  from  the 
surface  due  to  the  formation  of  crust  affects  the  ground  mass  but  does 
not  penetrate  the  chondri. 


MACQUARIE  RIVER 

This  locality  (spelled  "  Macquaire  "  River)  was  listed  in  the  appendix 
of  Wulfing's  catalogue*  and  specimens  were  mentioned  as  possessed  by 
Gregory,  58  grams,  Paris  School  of  Mines,  i  gram,  and  v.  Siemaschko, 

*  Die  Meteoriten  in  Sammlungen,  Tubingen,  1897,  p.  402. 


JULY,  1914.  NEW  METEORITES  —  FARRINGTON.  13 

3  grams.  The  classification  was  given  as  mesosiderite  or  pallasite, 
each  with  an  interrogation  mark,  and  the  date  of  find  as  1857.  It  was 
queried  also  by  Wulfing  whether  this  find  should  be  united  with  Cowra. 
With  the  purchase  of  the  Gregory  collection  by  the  late  Prof.  H.  A.  Ward 
the  58  gram  specimen  passed  to  Ward*  who  listed  it  as  a  mesosiderite 
and  gave  the  locality  as  latitude  31°  30'  S.  and  longitude  152°  56'  E. 
Meunierf  classed  Macquaire  River  as  logronite  and  described  it  as 
follows:  "We  have  only  a  small  piece  of  this  meteorite;  but  in  spite  of 
its  weight,  which  does  not  exceed  i  gr.,  there  is  sufficient  for  exact 
determination  and  without  hesitation  we  include  it  among  the  type 
logronite."  In  the  catalogue  of  the  Berlin  collection  by  Klein,  in  1906, * 
13.5  grams  of  Macquaire  River  were  listed  and  classed  (p.  13)  as  a  meso- 
siderite. Klein  also  (p.  103)  gave  the  following  description:  "Shows 
megascopically  much  iron  but  finely  distributed.  In  this  section  the 
silicates  appear  much  decomposed,  but  a  little  chrysolite  is  clearly  seen." 
Anderson  §  listed  Macquaire  River  among  the  Australian  meteorites 
and  its  possessors  as  Ward-Coonley  and  the  Berlin  Museum.  The  above 
seems  to  be  all  the  information  that  has  h'therto  been  published  regard- 
ing this  supposed  meteorite. 

On  the  acquisition  of  the  Ward-Coonley  Collection  by  the  Museum, 
the  58  gram  specimen  came  to  the  attention  of  the  writer  and  as  some 
of  its  characters  seemed  unsatisfactory  from  the  meteoric  standpoint, 
it  was  given  further  study.  The  specimen  is  a  fragment  thinner  than 
broad,  having  a  polished  surface  of  about  12  sq.  cm.  The  unpolished 
surface  is  of  iron-black  color,  the  polished,  nickel-white  to  bronze.  The 
luster  throughout  is  metallic  and  the  mass  is  magnetic.  The  unpolished 
surface  is  rough  without  being  jagged,  but  is  especially  marked  by  sev- 
eral pits,  two  of  which  are  of  elongated  form  while  the  others  are  circular. 
The  diameter  of  the  circular  pits  is  about  2  mm.  while  the  elongated 
pits  are  from  10  to  15  mm.  long.  These  pits  are  too  regular  in  form  and 
have  edges  too  sharp  to  correspond  to  the  usual  type  of  surface  pittings 
on  meteorites.  The  polished  surface  appears  to  the  naked  eye  to  be  of 
nearly  uniform  color  and  luster,  but  with  the  lens  shows  numberless  dots 
of  a  bright  gray  metal  imbedded  in  a  dull-black  ground  mass.  The 
form  of  the  individual  dots  is  in  general  circular  but  they  are  usually 
grouped  into  elongated  forms  so  that  something  of  a  pattern  is  given  to 
the  surface.  The  appearance  of  a  mesosiderite  is  thus  somewhat  simu- 
lated, but  the  metallic  dotting  is  more  uniform  and  abundant  than  the 

*  Catalogue  of  the  Ward-Coonley  Collection,  1904,  p.  31. 

t  Revision  des  Lithosiderites,  1895,  p.  34. 

I  Studien  uber  Meteoriten,  Abh.  d.  Konigl.  Preuss.  Akad.  d.  Wiss. 

§  Records  Australian  Museum,  1913,  Vol.  X,  p.  61. 


14     FIELD  MUSEUM  OF  NATURAL  HISTORY  —  GEOLOGY,  VOL.  V. 

writer  has  ever  noted  in  a  mesosiderite.  Material  for  a  chemical  analysis 
of  the  specimen  was  obtained  by  boring  to  a  depth  of  2  cm.  in  the  mass. 
with  a  5  cm.  drill.  This  gave  about  1.9  grams  of  a  black,  magnetic 
powder  which  was,  except  for  a  little  gelatinous  silica,  completely  soluble 
in  hydrochloric  acid.  Analysis  by  H.  W.  Nichols  gave: 

Je 70.72 

Ni 0.23 

Co trace 

Cu 12.35 

Ag 0.17 

Pb 0.78 

Zn o .  94 

Mn trace 

S 13-29 

P trace 

C 0.35 

Si  62 O.27 


99.10 

A12O3,  Ca  O,  Mg  O,  and  alkalies  were  present  in  traces.  The  analysis 
shows  the  mass  to  be  chiefly  a  sulphide  of  iron  and  copper  with  probably 
much  of  the  iron  reduced  to  the  metallic  form.  It  cannot  be  considered 
of  meteoric  origin.  The  small  percentage  of  nickel  may  have  given  a 
qualitative  test  which  led  the  original  finder  to  assume  a  meteoric  nature. 

There  seems  to  be  little  doubt  that  the  material  is  of  artificial  origin, 
the  result  of  some  smelting  operation.  The  piece  may  have  been  broken 
from  some  hearth  accretion.  In  any  case  the  evidence  seems  to  warrant 
dropping  Macquarie  River  from  the  list  of  accepted  meteorites. 

SOUTH  BEND 

The  determination  of  the  specific  gravity  of  this  meteorite  by  the 
writer  in  his  original  description*  was  called  in  question  by  Dr.  Peter 
Tschirwinsky  in  a  note  to  the  writer  in  February,  1908.  Dr.  Tschirwin- 
sky  suggested  that  the  value  (4.28)  obtained  seemed  low  for  a  meteorite 
containing  so  much  metal.  Accordingly  a  new  determination  of  the 
specific  gravity  was  made  by  the  writer,  with  the  result  that  a  value  of 
4.91  was  obtained.  Evidently  some  error  was  made  by  the  writer  in  his 
first  determination,  and  Dr.  Tschirwinsky 's  kindness  in  pointing  out 
such  a  probability  is  gratefully  acknowledged.  Using  the  new  value  to 
obtain  a  determination  of  the  relative  proportions  by  weight  of  the 
nickel-iron  and  chrysolite  in  the  meteorite,  the  result  is : 

Nickel-iron  56.2%  Chrysolite  43.8% 

This  ratio  should  be  substituted  for  that  previously  given. 

*  Pubs.  Field  Col.  Mus.,  1906,  Geol.  Ser.,  Vol.  3,  p.  20. 


EXPLANATION  OF  PL.  I. 

Upper  figure,  Fig.  I.  Ahumada  meteorite  XVs- 

Lower  figure,  Fig.  2.  Section  of  Ahumada  meteorite  Xtf.     The  dark  portions 
are  chrysolite,  the  light,  nickel-iron. 


FIELD    MUSEUM   OF  NATURAL  HISTORY 


GEOLOGY,  VOL.  V,    PL. 


EXPLANATION  OF  PL.  II. 

Upper  figure.     Side  view  of  Bishop  Canyon  meteorite, 
Lower  figure.     Rear  side  of  Bishop  Canyon  meteorite, 


FIELD   MUSEUM   OF  NATURAL  HISTORY 


GEOLOGY,  VOL.  V,    PL.   II. 


EXPLANATION  OF  PL.  IV. 

Upper  figure,  Fig.  I.     Front  side  of  Davis  Mountains  meteorite,  X^. 
Lower  figure,  Fig.  2.     Rear  side  of  Davis  Mountains  meteorite,  XV». 


FIELD   MUSEUM   OF  NATURAL  HISTORY  GEOLOGY,  VOL.  V,    PL.   IV. 


EXPLANATION  OF  PL.  V. 
Kilbourn  meteorite  shown  from  opposite  sides, 


FIELD   MUSEUM   OF  NATURAL  HISTORY 


GEOLOGY,  VOL.  V,    PL.  V. 


EXPLANATION  OF  PL.  VI. 

Upper  figure.    Board  penetrated  by  Kilbourn  meteorite  showing  character  of 
fracture  and  orifice  produced,  X#. 

Lower  figure.    End  view  of  Kilbourn  meteorite,  X^. 


FIELD   MUSEUM    OF  NATURAL  HISTORY 


GEOLOGY,  VOL.  V,    PL.  VI. 


10169 
5-22 


PEB     7 1978 


DATE  DUE 


FFR 


MWiiwiiiniiini 

A    001423231    8 


